Patent GB-460167-A (GB)
Title: Improvements in automatic clutch control devices
IPC: B60K23/02
Filed: 1936-03-06
Abstract: 460,167. Fluid-pressure servomotorcontrol systems. MAYBACH-MOTORENBAU GES. March 6, 1936, No. 6874. Convention date, March 27, 1935. [Class 135] The clutch of a motor vehicle is operated by a fluid-pressure servomotor so controlled that the clutch is disengaged upon release of the accelerator, is partially engaged when the accelerator is depressed to raise the engine speed above idling speed, the engaging pressure increasing with the engine speed, and is completely engaged when a predetermined engine speed is reached. With the engine idling, a valve 21<a> controlled by the accelerator 71 shuts off a pipe 3 from communication with a pipe 4 leading from a compressed air reservoir 1. Interconnected valves 103 and 104 are, under the differential action of springs 105 and 106 assisted by compressed air passing through a pipe 2, maintained open and closed respectively. The valve 103 affords communication between a servomotor 52 and an atmospheric air port 107 through a port 102, a longitudinal passage 101 in a valve 27b, a reduced portion 100 of the valve, and a passage 109. A spring 54, stronger than the clutch-engaging spring 17, is thus effective to disengage the clutch 15, 16 through a lever 57. Upon depression of the accelerator, the valve 21<a> connects the pipes 3, 4. A valve 27<a>, controlling communication between a pipe 46 and either the pipe 3 or an atmospheric air port 83, is so controlled jointly by an enginedriven governor 7, by a spring 28, and by the pressure in the pipe 46 acting through a port 84 on a diaphragm 78 secured to the valve, that the air pressure in the pipe 46 rises or falls with the engine speed. This air pressure acts on a piston 92 which, through a rod 93, moves a member 40 which, through a spring 98, controls the valve 27b. At the same time, a branch 86 of the pipe 3 supplies compressed air to a piston 108 whereby the valve 104 is opened, allowing compressed air to pass from the pipe 2 into a passage 110, and the valve 103 is closed, cutting off the communication between the passage 109 and the port 107. The passage 109 remains, however, in communication with an atmospheric air port 114 through a passage 111 and passages 94, 95 in the member 40. The valve 27b now acts to produce in the servo an air pressure which rises or falls with the engine speed. Thus, upon depression of the accelerator, the clutch spring 17 is effective to move the clutch parts into light engagment, and as the engine speed is further increased the clutching pressure increases therewith until, at a predetermined speed, a shoulder 96 on the member 40 closes the port 114. Due to leakage past the valve 27<b>, air pressure now builds up in the space 112 above the valve 27b, causing a further downward movement of the latter, and the full pressure of the compressed air is now communicated to the servo, allowing the spring 17 to be fully effective to complete the clutch engagement. When the accelerator is released during drive, pressure medium trapped in the conduits 3, 46, 86 leaks away very rapidly so that the clutch disengages.